Intro

The jpl
backend is an voltage recording system assembled by jpl and located
in the computer room. It is mainly used for planetary
radar xband,cband experiments (where jpl
transmits, and AO receives).
Some basic info

xband transmits at 8650 MHz.

the ao datataking routines:

located in the standard sband locations (astro/sband).

xbinit is used to do the setup

this calls xbconfig.. which does the configuration.

the ifsetup:

done by xbconfig

It is also possible to setup the if/lo independent of the
sband routines

vxWorks routine: xbjplsetup (in
/home/online/Tcl/Proc/gen)

This is always available from the vw% prompt.

It just sets up the AO if/lo. it does not move the turret
(eg. turpos xb)

The setup is:

rf cfr 8560

2-12 GHz mixer used

lo side 1st lo..

mixes 8560 to 1500 MHz 1st IF

this is unflipped.

2nd lo mixing:

use band 4

mix 8495 MHz to 260 MHz with low side lo

rf center of 260 MHz band is 8495 MHz. the band is
unflipped.

The device wants an IF freq of 325MHz.

325MHz is 65 MHz above 260 MHz

adding 65 MHz to the rf freq of 260IF gives 8560
(the freq of the xmiter)

SUMMARY:

an xband tone transmitted into the dome from the control room
appeared at the correct position in the spectral output of the
jpl backend.

the band input to the jpl backend is in increasing frequency
order. I checked the tone location on the spectrum analyzer at
the backend input. RfCfr 8560 (325 MHz at IF2), tone at 8561,
appeared at 326 MHz in the IF2 input to the backend.

The optimum histogram setting is giving an output with
1sigma=36 counts. This is more than is needed for optimum noise
statistics. A sigma of 20 counts for the 8 bit digitizer would
give more headroom.

Notes on doing the tone experiment:

vw%: turpos xb

vw%: xbjplsetup

if2mp (should be around -34)

if not adjpwrif2 -e 2 increase 2 to add
more power, decrease for less power.

tone:

xb helix. connect to 20 GHz hp synth. freq: 8561, amp:15 dbm

Check on spectrum analyzer in control room

1st IF output (through 40 db amp to spectrum analyzer).

cfr 1501, span 100 kHz.

web browser:

turn on power to rcver, amp

got to synth page and turn on rf for synth

login to jpl cpu

run datataking program

17 .. get hist

adjust power via ao vxworks

1 take data

10 secs

-1 exit

Use FCB routines to extract file, send to ao computers

Use idl to process data.

processing:x101/160817/jplrcvr.pro

160922: xband tone to check digital
receiver.

Clement modified the fpga code to support IF's of
260 and 325 MHz. On 22sep16 i rechecked the system by generating an
xband tone and receiving with the xband receiver. It was then passed
to the jpl digital receiver.

When logging into the jpl cpu : ssh
clement@192.231.95.51 i had to wait for many
minutes before the password prompt appeared. After entering
the password things worked normally. There was probably
something hanging on trying to access the nameserver.

processing: x101/160922/jplrcvr.pro

161027: testing the backend linearity

The variable attenuators were used to test the
linearity of the digital backend. The setup was:

xband receiver setup to give power level requested by cwcDRVC
program when 6 db of attenuation was installed.